Method of removing iron and cobalt from a partially refined nickel matte

ABSTRACT

A partially refined fused nickel matte is energetically and thoroughly washed with a chloridizing substance such as nickel chloride. The use of a chloridizing substance, which is preferred to an oxidizing agent as in the case of the usual treatment in a Bessemer converter, leads to a considerably improved selectivity in the refining of nickel mattes.

I United States Patent [151 3,660,026 Michel et al. [4 1 May 2, 1972[54] METHOD OF REMOVING IRON AND [56] References Cited COBALT FROM APARTIALLY I T P T REFINED NICKEL MATTE UN TEDS 5 723,158 3/1903 Jenkins..23/183 X [72] Inventors: Francis Michel, Meudon Bellevue; Louis1365358 1921 Udy ct 31m 23 R Gandon; Roger Jean, both of L6 a 1,929,50210/1933 Levy et al. ..75/113 Pierre Fer, Le Plavre-caucriauville, all of2,733,983 2/1956 Daubenspeck ..23/l83 France [73] Assignee: LeNickel,Paris, France Primary E'mmi'fer oscar vertiz Assistant ExammerG. Alvaro[22] Filed: May 9, 1969 Att0rneyWenderoth, Lind & Ponack [2]] App]. No:823,385 [57] ABSTRACT A partially refined fused nickel matte isenergetically and [52] L5. Cl ..23/l83, 23/87, 23/200, thoroughly washedwith a chloridizing Substance such as 75/82 75/1 75/1 19 nickelchloride. The use of a chloridizing substance, which is [51] "Colg 51/04C221) 9/12 C0 1 g 53/04 preferred to an oxidizing agent as in the caseof the usual treat- C221) 23/00 ment in a Bessemer converter, leads to aconsiderably im- [58] held of Search ..23/183, 87, 200, 134; 75/82,

Healing I0 300 850 C proved selectivity in the refining of nickelmattes.

9 Claims, 1 Drawing Figure mall: fed [a raaJI/ng uni! Hydra of C0 LPATEMTEDW 2 m2 3. 660,02 6

Heafing [a 8oo'- 850'C matte Ch/oridizin Anhy 7%5 liquid racy: LA ma Newafer 7 IL; I? 3 Chloride of Ni {Chioridcs of (all; 1 Aqueous 8 Jul/3T6w Iron removal (h loride I 01 Hgdrale of C0 Purified Chloride of NiSteam Purified V mall: fad (o "li /'3" of H d road/n5 unit of CaMaw-'01:: MICHEL, LOUIE; U/nHIIOH, HOGF'ZF: JEAN, and PIERRE; EER,[rn/mhr ts Attornr-ys METHOD OF REMOVING IRON AND COBALT FROM A PARTIALLYREFINED NICKEL MATTE This invention relates to the removal of the ironand cobalt from a partially refined nickel matte.

The removal of the iron and cobalt contents of a nickel matte preparedby a metallurgical process is carried out at present by usingpyro-smelting processes or chemical or electrochemical processes. Apyro-smelting or pyrometallurgical process consists essentially ineffecting a thorough removal of the iron content of a nickel matte in aBessemer converter by blowing air and injecting silica, and subsequentlycarrying out a thorough cobalt removal also by blowing air, theentrained highnickel slag gangues being recycled.

The inconveniences characterizing this known method are on the one handan indisputable lack of selectivity between the cobalt and nickel inregard to oxygen, which is attended by considerable amounts of nickelbeing entrained in the slag, and on the other hand the loss of thecobalt content in the slags which is not recoverable.

Moreover, this process burdens the nickel matte manufacturing line andincreases considerably the cost of this matte.

The refined matte obtained by this process is subsequently roasted forproducing nickel oxide and the latter is subsequently reduced to preparepure nickel.

The scope of the hitherto known chemical and electrochemical processes,beginning from an initially partially refined matte containing forinstance 76 percent Ni, 2 percent Co and 2 to 3 percent Fe, consists ofelaborating high-purity nickel metal (minimum Ni content 99.9 percent)and extracting the cobalt content in a commercially easily exploitableform, such as the hydrate of cobalt or its salts.

From the point of view of iron and cobalt removal, these processes havein common an iron, nickel and cobalt separation in an aqueous nickelsolution (nickel sulfate or nickel chloride, or in most instances nickelchloride sulfate) through conventional oxidation and hydrolysis methodsapplied to the iron in the form of ferric iron and to the cobalt in theform of trivalent cobalt.

These methods, for the elaboration of nickel metal and the cobaltextraction, imply the construction of complete chemical orelectrochemical equipment which, under present economic conditions, arefinancially advantageous only if very large amounts of pure nickel mustbe produced.

lt is an essential object of the present invention to provide a methodof removing iron and cobalt from a partially refined nickel matte bycombining the above-mentioned pyrometallurgical and chemical processeswhile avoiding the inconveniences of each.

The method of this invention is characterized in that a partiallyrefined nickel matte is energetically and thoroughly washed in a fusedstate with nickel chloride as a chloridizing substance. The use of suchchloridizing substance, which is preferred to an oxidizing agent as inthe case of oxidation in a Bessemer converter, leads to a considerablyimproved selectivity in the refining of nickel mattes.

Furthermore, nickel chloride is easy to prepare according toconventional methods in the nickel industry and is free of noxious anddangerous elements, other than chlorine of course.

The energetic washing of the matte with nickel chloride is carried out,according to this invention, by mixing and stirring the nickel chloridewith the nickel matte either by using a mechanical stirring devicesecured permanently or detachably to the ladle in which the mixing takesplace, or by any other suitable and known stirring means, such as byblowing neutral gas, notably argon or nitrogen.

When the fused nickel matte is washed with nickel chloride, according tothe method of this invention, the cobalt sulfide and iron sulfide areselectively decomposed by the nickel chloride to release cobalt chlorideand iron chloride. In order to permit the recovery of these cobalt andiron chlorides, it is contemplated according to this invention to add asuitable solvent for these chlorides to the nickel chloride used as achloridizing agent in the washing operation, the solvent being e-nn forexample potassium chloride, to avoid the release of gases whilepermitting the recovery of the chlorine as well as the metals.

Then the refined nickel matte is separated from the chlorides by adifferential density method, which is advantageous in that itfacilitates the separation of the chlorides from the matte in a suitableapparatus, before casting or granulating the matte.

The recovery of cobalt and the elimination of iron are effected,according to this invention, from an aqueous solution readily obtainedwhen pouring the chlorides in water, this procedure being advantageousin comparison with hitherto known chemical or electrochemical processesin that this solubilization is carried out by using a lesser number ofsteps. In fact in the known chemical processes many operations such ascasting the matte, then crushing, grinding and sieving, and eventuallylixiviating, are necessarily inserted between the production of themolten matte and forming of the aqueous nickel solution. In theelectrochemical processes the operations inserted between production ofthe molten matte and the aqueous nickel solution are casting the mattein the form of anodes, fitting the anodes in the electrolytic cells, andcarrying out electrolysis proper of these anodes.

The regeneration of nickel chloride by extracting the iron and cobaltcontents thereof and recycling the purified nickel chloride issubsequently carried out through conventional chemical methods.

The method of this invention permits an advantageous and simplevaporization of the cobalt from the hydrate of cobalt extracted duringthe purification of nickel chloride. It is known that inpyrometallurgical refining processes the cobalt content is entrained inthe slag and that it is extremely difficult and costly to recover thecobalt from this slag. It is also known that in chemical processes thecobalt is extracted only after a great number of other operations.

It is another feature of the present invention to permit the commercialconstruction of relatively simple units for carrying out thishigh-efficiency matte refining method, which comprises a smelting block,in which a nickel-bearing substance (such as a nickel matte) is mixedwith a chloridizing substance (such as nickel chloride), and anotherunit for purifying impure nickel chloride. This high-efficiency refiningof the matte is advantageous, in comparison with other processes, inthat it affords a greater flexibility in the initial preparation ofmatte, whether highly-refined or unrefined, while permitting theinsertion, in an existing commercial plant and without resort to heavyinvestments, of complementary equipment capable of improving either thequality of the end products or the operation of the complete productionline.

In order to afford a clearer understanding of this invention there isillustrated in the accompanying drawing a block diagram showing thecomplete sequence of operations for removing iron and cobalt from amatte in conjunction with the purification of impure nickel chloride.This diagram comprises the following reference numerals and operations:

1 Smelting the matte,

2 Mixing the liquid matte with the nickel chloride and preferablypotassium chloride, preferably in a ladle equipped with an agitator,

3 Decanting and casting the matte into suitable equipment permitting theseparation of the matte and the chlorides,

4 Granulating the matte, or casting the matte into ingots,

5 Adding make-up nickel chloride to compensate for the nickel entrainedwith the hydrate of cobalt and increasing the nickel content in thematte,

6 Re-introducing purified nickel chloride for carrying out furthercobalt-removing operations,

7 Extracting as per 3 hereinabove the molten chlorides which consist ofa mixture of nickel chloride, potassium chloride (preferably), ironchloride and cobalt chloride,

8 Forming an aqueous solution of said chlorides, preferably in a vessel(ladle) equipped with an agitator,

9 Removing the iron content of the impure nickel chloride preferably inthe presence of potassium hypochloride and carbonate of nickel. However,any other suitable and conventional iron-removing process may beadequate in this case,

10 Removing the cobalt from the impure nickel chloride,

preferably by using trivalent nickel, such as Ni(OH l 1, 12 and 13Collecting the purified nickel chloride and subsequently concentratingit, preferably in a doublewalled steam-heated evaporator, followed bycrystallization performed preferably in a continuous centrifuge andstoving according to conventional methods, and recycling the purifiedand concentrated nickel chloride as per 6, and

14 Manufacturing nickel sulfate or chloride to be used as the basicmaterial in the elaboration of make-up nickel chloride 5, carbonate ofnickel 1S and trivalent hydrate of nickel 16.

The preparation of these various salts is carried out according toconventional methods not within the scope of the present invention. Adescription of such methods will be found for instance in GMELIN,Handbuch der Anorganischen Chemie," 8.Auflage, Nickel, Teil B, VerlagChemie 1966, on pages 482-484 for the preparation of nickel hydrate andon page 840 for the preparation of nickel carbonate, both from nickelchloride or nickel sulfate. The transformation of nickel sulfate tonickel chloride, for instance by reaction with chlorhydric acid, isdealt with on pages 560 and 566 of the same volume.

The following is an example illustrating a typical manner of carryingout this invention. In this example all the figures are to be understoodby weight, or as percentages.

A matte having the composition:

Fe 1.76% S 24.09%

i.e., for Ni 100 Fe 2.43 and Co 2.62, is introduced into a smeltingfurnace heated to a temperature of 900 to 1,000 C., and subsequentlycast into a mixing ladle with molten nickel chloride. In this examplethe composition of the nickel chloride assays as follows:

for Ni 100, C0 0.46

The matte and NiCl proportions are for example as follows: for matte100,

26.28 of anhydrous nickel chloride (with a 25% Ni content).

The mixture of matte and molten chloride is stirred about 15 minutes,whereafter the cobalt sulfide and iron sulfide decomposition reactionstake place. These reactions are CoS NiCl CoCl NiS FeS NiCl FeCl NiS Anexchange takes place between the cobalt, iron and nickel contents of thematte, on the one hand, and the chloride, on the other hand.

Thus, the nickel content in the matte increases and the refined matte(in the example considered herein) assays as follows:

Fe 0.02% S 23.87%

i.e., for Ni 100, Fe 0.026 and Co 0.157.

The unpurified nickel chloride assays as follows at the end of the mattepurifying operation for Ni 100, Fe =13 and Co= 17.

This impure nickel chloride is dissolved in water contained in a vesselequipped with an agitator.

The water proportion is 5.2] liters per kilogram of nickel contained inthe molten chloride.

This solution is subsequently purified in two steps, i.e., aniron-removing step followed by a cobalt-removing step.

In this example the iron-removing step comprises an oxidation of theearthy iron into ferric iron by using potassium hypochlorite 2 Fe KClO2l-l 2Fe KCl H, O and a hydrolysis of the ferric iron by using carbonateof nickel The amount of carbonate of nickel (containing 13 percent ofNi) introduced is 75 kilograms per kg of Ni treated in the impurechloride.

After the iron-removing operation the nickel chloride content is asfollows for Ni 100, Fe nil, Co= 14.4.

The iron precipitate is filtered through a filter-press; in thisexample, 860 grams of Fe are collected per kg of treated Ni.

The cobalt is removed by using trivalent nickel hydrate ac cording tothe following reaction The amount of hydrate of Ni introduced is l.05 kg(assaying 16% Ni) of hydrate of Ni per kg of treated Ni.

The cobalt hydrate precipitate is filtered by using a filter press. Thehydrate of cobalt thus collected contains 14.4 kg of Co per 100 kg oftreated Ni, and entrains one part of Ni per 5 parts of cobalt.

The pure nickel chloride solution is subsequently concentrated,crystallized in a continuous centrifuge and eventually stoved accordingto conventional methods.

Of course, the present invention should not be construed as beinglimited by the specific example described hereinabove, which is only forpurposes of illustrating the manner in which the invention may becarried out in practice;. Various modifications may be made withoutdeparting from the basic principles of the invention as set forth in theappended claims.

What we claim is:

l. The method of removing iron and cobalt from a partially refinednickel matte, and recovering the cobalt contained in the matte, withoutsubstantial loss of nickel, which consists essentially of energeticallywashing the matte in a fused state with anhydrous nickel chloride toform a mixture of fused chlorides, decanting the matte, separating thepurified matte from the fused chlorides, adding water to the fusedchlorides to form an aqueous solution of the chlorides, and treating theaqueous solution of the chlorides to recover the cobalt and the nickelchloride contained therein,

2. The method as set forth in claim 1, wherein the recovered nickelchloride is used for washing fresh quantities of the partially refinednickel matte.

3. A method of removing iron and cobalt from a partially refined nickelmatte, which consists essentially of energetically washing the matte ina fused state with a mixture of anhydrous nickel chloride and potassiumchloride.

4. A method of removing iron and cobalt from a partially refined nickelmatte, which consists essentially of energetically washing the matte ina fused state with nickel chloride and removing the resultant chloridesalts.

5. The method as set forth in claim 4, wherein the energetic washing bymeans of the nickel chloride is performed by mix ing and stirring thenickel chloride with the matte, said stirring being carried out by amechanical agitator constituting a permanent fixture of the ladle inwhich the mixing step is performed.

6. The method as set forth in claim 4 wherein the energetic washing bymeans of the nickel chloride is performed by mixing and stirring thenickel chloride with the matte, said stirring being performed by using amechanical agitator detachably mounted to the ladle in which the mixingstep is performed.

7. The method as set forth in claim 4, wherein the energetic washing bymeans of the nickel chloride is performed by mixing and stirring thenickel chloride with the matte, said stirring being performed by blowinga neutral gas through the mixture.

8. The method as set forth in claim 7, wherein said neutral gas consistsof nitrogen.

9. The method as set forth in claim 7, wherein said neutral gas consistsof argon.

2. The method as set forth in claim 1, wherein the recovered nickelchloride is used for washing fresh quantities of the partially refinednickel matte.
 3. A method of removing iron and cobalt from a partiallyrefined nickel matte, which consists essentially of energeticallywashing the matte in a fused state with a mixture of anhydrous nickelchloride and potassium chloride.
 4. A method of removing iron and cobaltfrom a partially rEfined nickel matte, which consists essentially ofenergetically washing the matte in a fused state with nickel chlorideand removing the resultant chloride salts.
 5. The method as set forth inclaim 4, wherein the energetic washing by means of the nickel chlorideis performed by mixing and stirring the nickel chloride with the matte,said stirring being carried out by a mechanical agitator constituting apermanent fixture of the ladle in which the mixing step is performed. 6.The method as set forth in claim 4 wherein the energetic washing bymeans of the nickel chloride is performed by mixing and stirring thenickel chloride with the matte, said stirring being performed by using amechanical agitator detachably mounted to the ladle in which the mixingstep is performed.
 7. The method as set forth in claim 4, wherein theenergetic washing by means of the nickel chloride is performed by mixingand stirring the nickel chloride with the matte, said stirring beingperformed by blowing a neutral gas through the mixture.
 8. The method asset forth in claim 7, wherein said neutral gas consists of nitrogen. 9.The method as set forth in claim 7, wherein said neutral gas consists ofargon.